Various types of electromagnetic fuel injectors are used in the fuel injection systems of internal combustion engines. Such injectors, as well as other solenoid controlled valve structures, have been used which have a solenoid armature located between the pole piece of the solenoid and a fixed valve seat whereby the armature operates the valve member. Examples of such electromagnetic fuel injectors or solenoid controlled valve structures are described in U.S. Pat. No. 4,515,129 issued May 7, 1985 to Stettner and U.S. Pat. No. 4,572,436 issued Feb. 25, 1986 to Stettner et al. The above identified patents show arrangements in which an armature/valve is biased to a normally closed position against a fixed valve seat by a spring member. The armature/valve is operable between a seated, sealing position against the valve seat and an open position against a pole piece of the solenoid for controlling flow through a fuel injector port in the valve seat.
In the past, fuel injectors have been used to inject fuel onto the back of the intake valve of the engine, such as the injector described in U.S. Pat. No. 5,577,481 issued Nov. 26, 1996 to Wahba. This type of fuel injector is known as a port fuel injector. Other injectors inject fuel into the engine's intake manifold. Recently, fuel injectors have been used to inject fuel directly into the cylinder of the engine. This type of injector is known as a direct injection injector. For direct injection, it is desirable to have the injector as small as possible to fit within the limited space surrounding each cylinder of the engine. Fuel injectors have typically had outside diameters of 22 mm or larger. When the size of an injector is reduced, it is difficult to design a solenoid which generates sufficient force, using a twelve volt system, to achieve the desired control and flow requirements.
Therefore, a fuel injector is needed which is relatively small in size, yet has a solenoid which generates sufficient force to achieve the desired flow of fuel through the injector.
In addition, fuel injectors are either outwardly opening or inwardly opening. In an outwardly opening injector, the valve moves down away from the solenoid to open and is drawn up into the valve seat to close. In an inwardly opening injector, the valve is drawn up toward the solenoid to open the injector and moves down into the valve seat to close the injector. It is desirable to have shared parts with these two types of injectors to increase manufacturing efficiencies.